2,3-dihydro-1,4-benzoxazines

ABSTRACT

The invention provides 3-oxo-2,3-dihydro-1,4-benzoxanines carrying a carbamoylakyl radical in the 4-position which have useful therapeutic properties as muscle relaxing agents, analgesics, anti-convulsion agents, anti-inflammatories, and anti-pyretics.

United States Patent Pesson Aug. 1,1972

2,3-DIHYDRO-1,4-BENZOXAZINES Inventor: Marcel Pesson, Paris, France Assignee: Societe anonyme dite: Laboratoire Roger Bellon, Neuilly-sur-Seine (Hauts de Seine), France Filed: June 4, 1968 Appl. No.: 734,223

Foreign Application Priority Data I June 6, 1967 Great Britain ..25,999/67 US. Cl ..260/244 R, 260/246 B, 260/247.2 A, 260/247.7 H, 260/268 C, 260/268 DK, 260/293.63, 260/293.77, 260/293.88, 260/293.89, 260/326.3, 260/326.5 E,

260/561 l-IL, 260/561 K, 260/562 B, 424/248 Int. Cl. ..C07d 87/48 Field of Search ..260/244, 244 R, 247.2 A

Chem. Abst'. Vol. 64, Subject Index (A-D) page 497 S (1966)QD1.A51.

lrving et al., J. Chem. Soc. (London) 1963, pages 3308- 3309 relied on QDl.c6.

Primary Examiner-Natalie Trousof Attorney-Gerard .l. Weiser 5 7] ABSTRACT The invention provides 3-oxo-2,3-dihydro-l,4-benzoxanines carrying a carbamoylakyl radical in the 4-position which have useful therapeutic properties as muscle relaxing agents, analgesics, anti-convulsion agents, anti-inflammatories, and anti-pyretics.

37 Claims, No Drawings 2,3-DIHYDRO-l ,4-BENZOXAZINES This invention relates to dibydro-l,4-benzoxazines,

their preparation and pharmaceutical compositions containing them.

in which R represents a hydrogen atom or a straight or branched lower alkyl radical, R R and R are identical or different and each represents a hydrogen atom, a straight or branched lower alkyl radical, a halogen atom, or a lower alkoxy radical, R represents a hydrogen atom, a lower alkyl radical, or a group of formula:

Re ON and R and R are identical or different. and each represents a hydrogen atom, an aryl radical (e.g. phenyl or tolyl), a lower alkyl radical, or a lowe hydroxyalkyl radical, or R and R taken together with the nitrogen atom to which they are attached, form a heterocyclic radical having five or six ring members which may contain hetero-atoms other than the nitrogen, such as pyrrolidyl, piperidyl, morpholinyl or piperazinyl. By lower alkyl is meant alkyl of one to six carbon atoms.

The compounds of formula I have valuable pharmacological properties on the central nervous system. They act as muscular relaxing agents, analgesics, antipyretics and anti-convulsion agents. Some of them furthermore have anti-inflammatory properties.

The compounds which combine anti-inflammatory and analgesic properties and an anti-pyretic effect are especially valuable.

According to a feature of the invention, the compounds of formula I are prepared by reaction of an acid halide, e.g., chloride, of an acid of formula:

l (EHCOOH with ammonia or an amine of formula:

it a

llN

R1 III wherein the various symbols are as hereinbefore defined.

The starting materials of formula II are prepared from a 3-oxo-2,3-dihyd.rol ,4-benzoxazine of formula:

where R R R and R are as hereinbefore defined, whose alkali metal salt is condensed with a lower alkyl ester of the formula:

Rs V

where X is halogen, R is lower alkyl, and R is as hereinbefore defined, to yield the corresponding ester, which is then saponified to yield the acid of formula II.

The condensation of the alkali metal salt of the 3- oxo-2,3-dihydro-l,4-benzoxazine of formula IV and the a-halogenoester of formula V is best carried out in a lower alcohol, preferably tertiary butanol. The salt is itself prepared in situ by adding the 3-oxo-2,3- dihydrobenzoxazine to a solution of an equimolecular amount of the alkali metal alcoholate obtained by dissolving one equivalent of the metal in an excess of the selected alcohol. The reaction is continued by adding a slight molar excess (about 10 percent) of the ahalogenoester and heating under reflux with stirring until the medium, which is initially alkaline, is neutral. This requires 2 to 4 hours. The inorganic salts are filtered off while the solution is still hot. After evaporating the solvent, preferably in vacuo, the ester of the acid of formula II is precipitated by adding water. Sometimes the ester crystallizes spontaneously; it is then filtered and recrystallized from a suitable solvent. Generally, however, the ester forms an oily or semicrystalline mass, which is extracted with an appropriate solvent, and the organic solution is dried and the solvent evaporated. The residue is then recrystallized from a suitable solvent. Where they are not crystalline, the esters may optionally be distilled in a high vacuum or used without further purification, for the next operation.

The esters of formula V may be chloro, bromo, or iodo esters. In the case of the a-chloroesters it is possible to increase the speed of reaction by adding a small amount of potassium bromide or iodide to the reaction medium. To increase the reaction speed it is also possible to work in a mixture of solvents containing about 50 percent of dimethylforrnamide, which makes it possible to raise the temperature of the medium to l00-l 10 C.

The acids of formula II are easily obtained in manner known per se by saponifying the corresponding esters with an alkali metal hydroxide, preferably potassium hydroxide, in an aqueous alcoholic (e.g., ethanolic) medium. This process is generally rapid (l to 2 hours) at the reflux temperature of the alcohol. When the saponification is complete, the solvent is driven off, the residue is dissolved in water, and the acid liberated, generally in the solid state, by acidification with a strong inorganic acid. The acid is then filtered off and recrystallized from a suitable solvent.

The conversion of the acids of formula II into the compounds of formula I is conveniently carried out via the corresponding acid chlorides which can easily be obtained by reacting a slight excess (1.l mols) of thionyl chloride with 1 mol of the acid in a neutral solvent (e.g. benzene, chloroform, or toluene). If necessary, a

small amount of a catalyst such as pyridine or dimethylformamide may be used. The reaction is conveniently carried out at 6080 C. When it is ended, the solvent and the excess thionyl chloride are driven off in vacuo.

The crude acid chloride is dissolved in a non-polar neutral solvent such as an aromatic hydrocarbon, chloroform or methylene chloride. This solution is added, with vigorous stirring and cooling in ice, to an excess (3 to 5 mols) of the amine of formula III itself dissolved in a neutral solvent such as an aromatic hydrocarbon, chloroform or methylene chloride. After the reaction, the organic solution is filtered to remove the amine hydrochloride which has precipitated, and is then successively washed with a dilute solution of a strong inorganic acid (to remove excess amine), a dilute solution of an alkali metal hydroxide (to remove any acid of formula II) and then with water. After drying, the solvent is evaporated and the residue is recrystallized from a suitable solvent. It is possible to proceed to the acid and basic wash operations without filtering off the amine hydrochloride.

Where volatile bases of formula III which are very soluble in water are used, such as ammonia, methylamine or dimethylamine, it can be of value to proceed by adding the organic solution of the acid chloride to an excess of the amine in aqueous solution. It can then happen that the compound of formula I precipitates at the water/solvent interface. If this happens, it is filtered off and recrystallized from a suitable solvent.

When the compounds of formula I are not immediately obtained in the crystalline state, they may be distilled in a high vacuum to purify them sufficiently for crystallization to be possible.

According to a further feature of the invention, the compounds of formula I are prepared by reaction of an alkali metal salt of a 3-oxo-2,3-dihydro-l ,4-benzoxazine of formula IV with an a-halogenoamide of formu- Iii: Rr VI where X, R R and R are as hereinbefore defined. The reaction is preferably carried out in a lower alcohol, preferably tertiary butyl alcohol, in which the salt of the compound of formula IV is prepared in situ as in the preceding method. A slight excess (10 percent) of the amide of formula V1 is added to the solution of this salt, and the reaction, which frequently begins even at ordinary temperatures, is continued with stirring at the reflux temperature of the alcohol used. When this operation is complete (as indicated by the initially alkaline medium changing to give a neutral or acid reaction) the solution is filtered hot to remove the precipitated inorganic salts. The solvent is removed in vacuo and the residue, which is generally crystalline, is taken up in water, filtered, and washed with a dilute solution of an alkali metal hydroxide (to remove unreacted 3-oxo-2,3-dihydro-l,4-benzoxazine). After drying, the product of formula I is recrystallized from a suitable solvent.

In the amides of formula VI, X may be chlorine,

bromine, iodine. When X is chlorine, the reaction may be catalysed by adding a small amount of potassium bromide or iodide to the medium.

The speed of reaction may also be increased by diluting the medium with an equal volume of dimethylformamide or dimethylsulphoxide. The process is then carried out at a temperature between and C.

With certain a-halogenoamides of formula VI whose halogen atom is particularly reactive, the reaction can be carried out at ambient temperature.

The second method, which is shorter, is particularly valuable when the a-halogenoamides of formula VI employed are tertiary. It also gives satisfactory yields with certain primary amides. With secondary ahalogenoarnides the formation, as by-products, of 2,5- dioxopiperazines substituted in the 3,6-position and resulting from the autocondensation of 2 molecules of the halogenated amide with the elimination of 2 mols of the hydracid, is sometimes observed. It is then preferable to use the first method. The second method is also useful when the a-halogenoamide of formula VI is an N,N'-tetrasubstituted-halogenomalondiamide.

The following examples illustrate the invention.

EXAMPLE 1 3-oxo-4-(morpholinocarbonylmethyl)-2,3-dihydro- 1 ,4-benzoxazine.

A solution of potassium t-butoxide is prepared by dissolving 6.55 g. of metallic potassium in 250 cm of tbutyl alcohol in a two-necked flask fitted with a stirrer, a reflux condenser and a dropping funnel. The solution, cooled to 40 C., is vigorously stirred and 26 g. of 3- oxo-2,3-dihydro-l ,4benzoxazine are added thereto, followed by 20.5 g. of ethyl chloroacetate dropwise. The mixture is heated under reflux, with stirring, for 7 hours. The solvent is driven off in vacuo and the residue is taken up in about 200 cm of water. The partially crystalline precipitate is extracted with diethyl ether. The organic solution is washed with water and dried over anhydrous magnesium sulphate. The solvent is driven off and the residue is recrystallized from diisopropyl ether. The 3-oxo-4-carbethoxymethyl-1,4- dihydrobenzoxazine so obtained melts at 78 C. The yield is 30.8 g. (79 percent).

Analysis:

Calculated f0! C12H13NO4, I 6 1 N% 5 .96;

Found: C%= 61.27; I-l% 5.62; N% 6.04.

20 g. of this ester are heated for 1 hour under reflux with 5.5 g. of potassium hydroxide in an aqueous alcoholic medium (200 cm of alcohol and 15 cm of water). The solvent is then driven off in vacuo, the residue is dissolved in water, and the solution is treated with animal charcoal, filtered, and then acidified with 4N hydrochloric acid. The precipitate is filtered off, washed with water and dried in vacuo over phosphorus pentoxide. The yield is 16.9 g. (92 percent) of 3-oxo-4- carboxymethyl-2,3-dihydro-l,4-benzoxazine, which, when purified by recrystallization from ethanol, melts at 231 C.

Analysis:

Calculated for C H NQ, C% 57.97; H% 4.38;

Found: C% 58.24; l-l% 4.58; N%= 6.79.

3.2 cm of thionyl chloride and 0.1 cm of anhydrous pyridine are added to this acid (8.3 g.) suspended in 40 cm of benzene. The mixture is heated for 1 hour under reflux and the solvent and excess thionyl chloride are then driven off in vacuo. The solid residue is dissolved in 60 cm of anhydrous chloroform and the solution is added dropwise to a vigorously stirred solution of morpholine (8.7 cm) in chloroform (60 cm cooled in an ice bath. After cooling to ambient temperature, the mixture is stirred for a further 2 hours and the precipitate is filtered off and then washed with chloroform. The combined organic solutions are washed first with 4N hydrochloric acid, then with water, then with 2N sodium hydroxide solution, and finally with water. After drying over magnesium sulphate, the solvent is driven off and the residue is recrystallized from benzene. The yield is 7.68 g. (69.7 percent). For analytical purposes, the 3-oxo-4- (morpholinocarbonylmethyl )-2,3-dihydro-1 ,4-benzoxazine is dried at 110 C./ mm. It then melts at 155-156 C.

Analysis:

Calculated for C I-1 N 0 C% 60.86; H% 5.84;

N%= 10.14; Found C%=60.83; H%=6.l l; N%= 10.24.

EXAMPLE 2 3-Oxo-4-(N-dimethylcarboxamidomethyl)-2,3- dihydrol ,4-benzoxazine The acid chloride solution to 60 cm of chloroform is prepared as described in Example 1 from 8.3 g. of 3- oxo-4-carboxymethyl-2,3-dihydro-1 ,4-benzoxazine. The solution is added dropwise to 22 cm of a 29 percent strength dimethylamine solution in chloroform which is vigorously stirred and cooled in an ice bath. When the addition is complete, the mixture is stirred for 2 hours at ambient temperature. After filtering and washing the precipitate with chloroform, the organic solution is successively washed with 4N hydrochloric acid, water, and 2N sodium hydroxide solution and then dried over magnesium sulphate. The solvent is evaporated and the solid residue is recrystallized from a mixture of benzene (1 vol.) and cyclohexane (2 vols.). it melts at 125126 C. The yield is 6.17 g. (66 percent). Analysis:

Calculated for C H N O C% 61.52; H% 6.02;

N%= 11.96; Found: C%=61.43;H%=6.12; N%= 11.99.

EXAMPLE 3 3-Oxo-4-carboxamidomethyl-2 ,3-dihydro-1 ,4-benzoxazine A solution of potassium t-butoxide obtained from 2.62 g. of metallic potassium and 100 cm of t-butyl alcohol is vigorously stirred and 10.1 g. of 3-oxo-2,3- dihydrobenzomorpholine are added to it. After stirring for 15 to minutes at ordinary temperatures, 6.5 g. of chloracetarnide are added and the mixture is heated for 4 hours under reflux. After cooling, the insoluble products are filtered off, and the solvent is evaporated. The residue is combined with the insoluble part and the whole is taken up in 200 cm of water. The solid product is filtered off and washed with 2 X 50 cm of sodium hydroxide solution to remove unreacted 3-oxo- 2,3-dihydro-l,4-benzoxazine. It is then washed with water and dried. The yield is 10.54 g. (76.3 percent). After purification by recrystallization from dimethylformarnide, 7.42 g. of 3-oxo-4-carboxamidornethyl-2,3 -dihydro- 1 ,4-benzoxazine are obtained, m.p. 260 C. Analysis:

Calculated for G Q-1 N 0 C% 58.25; H% 4.89;

N%= 13.58; Found: C%=58.32; H%=4.97; N%= 13.53.

EXAMPLE 4 3-Oxo-4-(N-o-tolylcarboxamidomethyl)-2,3-dihydro- 1 ,4-benzoxazine A solution of potassium t-butoxide is prepared by dissolving 2 g. of potassium in cm of t-butyl alcohol. When the temperature has dropped to 30-40 C., 7.45 g. of 3-oxo-2,3-dihydro-1,4-benzoxazine are added with stirring, followed by 10.08 g. of chloracetylo-toluidine. After 2 hours stirring at ambient temperature, the contents of the flask (which have set solid) are diluted with about 100 cm of ethanol. The solid is filtered off, washed with water to dissolve the inorganic salts, and recrystallized from dimethylformamide. The yield is 9.14 g. (61.6 percent), m.p. 229 C. Analysis:

Calculated for C I-1 N 0 C% 68.90; H% 5.44;

N% 9.45; Found: C%=68.57; H%=5.35; N%=9.39.

EXAMPLE 5 3-Oxo-4-carboxamidomethyl-6-butyl-2,3-dihydro-1 ,4- benzoxazine About 10.25 g. of 3-oxo-6-butyl-2,3-dihydro-1,4- benzoxazine followed by 50 cm of anhydrous dimethylformamide are added at 50 C. to a solution of potassium t-butoxide prepared as in the preceding Examples from 2.05 g. of metallic potassium and 50 cm of t-butyl alcohol. The mixture is stirred until a clear solution is obtained and 0.125 g. of potassium iodide followed by 5 g. of chloracetamide are then added. Stirring is continued while the temperature is kept at C. until the medium is neutral. The greater part of the solvents is removed on a water bath in vacuo. The residue is taken up in 500 cm of water. The precipitate is extracted with benzene (500 cm), and the organic solution is washed with 2N sodium hydroxide solution and then with water. After drying over magnesium sulphate and evaporating the solvent, the residue is recrystallized from a mixture of ethyl acetate and hexane. The yield is 9.22 g. (70 percent), m.p. 142 C. Analysis:

Calculated for C I-1 N 0 C% 64.10; I-l% 6.92;

Found C%=64.03; l-l%=6.90; N%= 10.80.

Tables I and Il give the constants of compounds of formula 1 in which R H, prepared in accordance with the methods described above. The products of Examples 35 and 36 were prepared by the first method. The corresponding acid was obtained as described in Example l. Condensation of the potassium salt of 3-oxo-6- chl0ro-2,3-dihydrobenzoxazine and ethyl chloracetate yielded 3-oxo-4-carbethoxymethyl-6-ch1oro-2,3- dihydro-l ,4-benzoxazine, m.p. C. (after recrystallization from a mixture of cyclohexane and ether) Analysis:

Calculated C% 53.44; H% 4.49; N% 5.19;

Cl% 1 3. 15; Found: C% 53.29; H% 4.48; N% 4.97; Cl%

13.16 Saponification of this yielded 3-oxo-4-carboxymethyl-6 -chloro-2,3-dihydro-1,4-benzoxazine, m.p. 197 C. (after recrystallization from ethyl acetate). Analysis:

Calculated C% 49.70; l-l%= 3.34; N% 5.80;

Cl% 14.67; Found: (3% 49.92; l-l% 3.20; N% 6.00; Cl%

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C1aN1 ClN 20s 7o 01H; (31 -CH; R5=R1=CH5 2nd... 7? 151 methanol 57.96 9.01 6.61 11.41 57.90 9.21 6.36 11. 50

C 11ClN201 I 71 0 H, Cl 'CH5 Q 2nd... 74 l-ilmethanol 61.61 7.98 6.60 10.10 61.29 8.09 5.64 10.35

CHHQCINQOS 72 H (:1 CH5 R5=R1=H 2nd... 335 230/232(DMF) 51.50 11.00 0.35 13.02 51.73 11.22 4.53 13.85

CnHizClNzOa 73 H 01 on; R5=R7=CH3 2nd..- 77 189/190(n) 55.22 0.01 5.35 12.54 55.50 0.05 5.55 12.44

C1:H15CIN2O3 74 H 01 CH: o 200...." 82 150 5 50.52 5.57 5.92 10.03 50.21 3.54 5.00 11.17

75 ..1 Br 0H5 R5=R1=H 2nd. 41 237 5) 4418 9.37 3.70 44.05 0.35 3.35

C11H11B1N203 70 11 Br' CH5 R0=Ry=OHa 2nd 77 104 5 47.70 8.78 4.52 47.74 8.78 4. s1

CnHigBrNzoa 77 H H 01 R5=R7=H 2nd.. 75 257 40.01 11.04 3.77 14.73 40.75 11.55 3.51 14.59

78 H H 01 Ru=R7=CH3 2nd 50 100 5) 53.63 10.43 4.57 13.20 54.00 10.43 4.57 13.20

CrfirgClNzOa 70 .r1 H 01 O 2nd 00 l56(g./c.) 53.35 3.07 5.55 11.45 55.20 0.07 5.55 11.45

CuHnClNzO;

s0 H H CH5 R0=R7=-CH5 2nd 110 1300;) 02.50 11.23 5.50 5200 11.33 5.34

EXAMPLE 81 EXAMPLE 82 0.5 cm of dimethylformamide are added to 8.6 g. of 3-Oxo-4-(a-piperidinocarbonylether)-2,3-dihydro-1,4-

3-oxo-4-carboxymethyl-6-chloro-2,3-dihydrol ,4- benzoxazine benzoxazine suspended in 60 cm of thionyl chloride As in Example 1, 44.7 g. of 3-oxo-2,3-dihydro-l,4'-

and the mixture is heated to 60 C. for 5 hours. The exbenzoxazine are addedto asolution of potassium t-bucess reagent is removed in vacuo and the residual acid chloride is taken up in cm of benzene which are then evaporated in vacuo. This operation is repeated twice more to remove the thionyl chloride as completely as possible. The residue is dissolved in 60 cm of benzene and the solution is added dropwise to 40 g. of an aqueous 40 percent strength solution of dimethylamine. After standing overnight at ambient temperature, the precipitate formed at the interface of the solution is filtered off and recrystallized from ethyl acetate. 4.95 g. of 3-oxo4(N-dimethylcarboxamidomethyl )-6-chloro-2,3-dihydro-l ,4-benzoxazine, identical to the product of Example 35, are obtained.

toxide prepared from 12 g. of metallic potassium and 350 cm of t-butyl alcohol, and 54.3 g. of ethyl orbromopropionate are then added with stirring. The reaction is practically instantaneous (as shown by the formation of a copious precipitate of potassium bromide), and is completed by heating under reflux for 1 hour with stirring. The solution is filtered and evaporated to dryness. An uncrystallizable oil is obtained which is saponified without further purification.

The crude ester is added to an aqueous alcoholic solution (500 cm of ethanol and 40 cm of water) of potassium hydroxide (17.4g.) and the whole mixture is heated under reflux for 2 hours. The solvent is driven off in vacuo and the residue dissolved in 400 cm of water. The aqueous solution is extracted with diethyl ether and then acidified by adding hydrochloric acid. The 3-oxo-4-(a-carboxyethyD-Z,3-dihydro-1 ,4- benzoxazine which precipitates is filtered off, washed with water, dried and recrystallized from ethyl acetate (using animal charcoal). The yield is 42 g. (63.5%), m.p. 172 C. Analysis:

Calculated for C H NQ, C% 59.72; H% 5.01;

8.85 g. of this acid are converted into the corresponding chloride as described in Example 1, by reaction with 3.2 cm of thionyl chloride and 0.1 cm of pyridine in 40 cm of benzene. To avoid the formation of strongly colored products it is advisable to stop the heating under reflux when the acid has completelydissolved. After evaporating the solvent, the residue is dissolved in 50 cm of chloroform and the solution is added, as described in the same Example, to a cooled, stirred solution of 8.5 g. of piperidine in 40 cm of chloroform. After stirring (2 hours) at ordinary temperatures, the mixture is washed with 3N hydrochloric acid and then with 2N NaOl-I and water. The chloroform solution is dried over magnesium sulphate, and evaporation of the solvent leaves an oil which, since it does not crystallize, is distilled in a high vacuum b.p. 170-176 C./0.25 mm.Hg. The distilled oil crystallizes when treated with hexane. The yield is 5.82 g. The 3-oxo-4-(a-piperidino-carbonylethyl )-2,3-dihydro-1 ,4- benzoxazine is purified by recrystallization from hexane, m.p. 80 C.

Analysis:

Calculated for C H N O C% 66.64; H% 6.99;

N% 9.72; Found: C%=66.73; H%=7.25; N%=9.67.

EXAMPLE 83 3-Oxo-4-(a-dimethylcarboxyamidoethyl)-2,3-dihydrol ,4-benzoxazine The acid chloride prepared as in Example 51, dissolved in 40 cm of chloroform, is added to 90 cm of a percent strength solution of dimethylamine in benzene. After the usual treatment, the amide is purified by recrystallization from ethyl acetate. The yield is 6.25 g. (63.1 percent), m.p. 155 C.

Analysis:

Calculated for C H N O C% 62.89; H% 6.50;

N% l 1.28; Found: C%= 63.02;H%=6.55;N%= 11.31.

EXAMPLE 84 3-Oxo-4-(a-diethylcarboxyamidoethyl)-2,3-dihydro- 1,4-benzoxazine This amide is obtained as in the preceding examples, by reaction of the appropriate acid chloride with diethylamine in chloroform solution. The yield is 55 percent, m.p. 9091 C. after recrystallization from hexane. Analysis:

Calculated for C H' N O C% 65.19; H% 7.30;

N% l 0. 14; Found C%= 65.27; 11% 7.60; N%= 10.40.

EXAMPLE 85 3-Oxo-4-( a-pyrrolidinocarboxylethyl )-2,3-dihydro- 1 ,4-benzoxazine This compound is obtained as in the preceding examples from the corresponding acid chloride and pyrrolidine. It is a white solid, m.p. 80 C. (after recrystallization from a mixture of hexane (100 v.) and diisopropyl ether (100230 v/v)).

Analysis:

Calculated for C I-1 N 0 C% 65.67; H% 6.61;

N l 0.21 Found: C%=65.66; 11% 6.771; N%= 10.15.

EXAMPLE 8 6 A solution of potassium t-butoxide is prepared from 2 g. of potassium and 100 cm of t-butanol in the apparatus described in Example 1. 8.86 g. of 2-ethy1-3- oxo-2,3-dihydro-1,4-benzoxazine followed by 17.4 g. of N,N-penta-methylenebromo-malondiamide are added to the solution with good agitation while it is still warm. After heating under reflux for 2% hours, the solvent is distilled off in vacuo, the residue is taken up in water (100 cm"), and the mixture is extracted with diethylether. The organic extract is washed 3 times with 2N sodium hydroxide solution and then with water, and then dried over anhydrous magnesium sulphate. Evaporation of the sulphate leaves a viscous residue which crystallizes after treatment with 150 cm of petroleum ether. 5-Ethyl-3-oxo-4-bis(N-pentamethylenecarboxyamido )methyl-2,3-dihydro-1 ,4- benzoxazine (13.31 g.) is filtered off and recrystallized from diisopropyl ether. The yield is 10.96 g. (53 percent), m.p. 138 C. Analysis:

Calculated for C H N O C% 66.80; 11% 7.5 6;

N% 10. l 6; Found C%=67.33; H%=7.78;N%= 10.17.

EXAMPLE 87 N,N-Pentamethylenebromo-malondiamide is reacted with the potassium salt of 3-oxo-2,3-dihydro- 1,4-benzoxazine by the procedure described in Examamido)-methyl-2,3-dihydro-1 ,4-benzoxazine ple 86, and 3-oxo-4-bis(N-pentamethylenecarboxis obtained in a yield of 57 percent after recrystallization from ethyl acetate, m.p. 184 C.

Analysis:

Calculated for C I-1 N 0 C% 65.43; H% 7.06;

N%=l0.90; Found:-C%=65.S1;N%=6.80;H%= 11.03.

EXAMPLE 8 8 tion from ethyl acetate.

Analysis:

Calculated for C I-1 N 0 C% 66.14; H% 7.32;

N% 10.52; Found C% 66.36; 11% 7.56; N% 10.62.

EXAMPLE 89 3-.Oxo-4-bis( N-pentamethylenecarboxamido)methy1-6-chloro-2,3-dihydro-1 ,4-benzoxazine is prepared by the process in Example 81 from the potasunru-v nusium salt of 3-oxo-6-chloro-2,3-dihydro-1,4-benzoxazine, and is obtained in a yield of 63 percent after recrystallization from a mixture of benzene and cyclohexane,m.p. 145 C. Analysis:

calculated for C21H23C1N304 6.24; N%= 10.00 Found C%= 60.00; I-l%= 6.48; N%= 10.05.

EXAMPLE 91 Proceed as in Example 90 from appropriate starting materials, 2-ethyl-3-oxo-4-bis(N-dimethylcarboxamido)methyl-2,3-dihydrol ,4-benzoxazine is obtained in a yield of 43 percent after recrystallization from diisopropyl ether. It melts at l l6l 17 C.

Analysis:

Calculated for C I-1 N C% 61.24; H% 6.95;

N% 12.61 Found C%= 61.27; H%= 7.08; N%= 12.66.

EXAMPLE 92 Proceeding as in Example 90 from appropriate starting materials, 3-oxo-4-bis(N-dimethylcarboxamide )methyl-6-methyl-2,3-dihydro-l ,4-benzoxazine is obtained in a yield of 31 percent after recrystallization from a mixture of benzene and cyclohexane, mp. 205 C.

Analysis:

Calculated for C l-1 N 0 C 60.17; 11% 6.63;

N% l 3. l 6; Found: C% 60.23; 11% 6.80; N%= 13.01.

EXAMPLE 93 3-Oxo-4-bis( N-dimethylcarboxamido)methy1-6- chloro-2,3-dihydro-1,4-benzoxazine is obtained by the procedure of Example 90 from appropriate starting materials in a yield of 43 percent. After recrystallization from methanol, it melts at 199 C. Analysis:

Calculated for C H ClN O C% 53.02; H%

5.34; N%= 12.27; Cl% 10.43. Found: C%=53.0l; H%=5.71; N%= 12.26; Cl%= 10.68. The compounds of the invention have been studied by the following test methods: Toxicity The lethal dose (LD 50) was determined intraperitoneally and orally for batches of five to male mice weighing 18 to 25 g., and calculated by the method of probits.

Analgesic Effect (Siegmund test in mice).

Pain is caused by intraperitoneal injection of a 2 percent aqueous alcoholic solution of phenyl-para-quinone, which causes characteristic dropping of the rear quarters during movement. The compound studied was orally administered 30 minutes previously. The number of syndromes manifested in one batch of mice during 5 minutes observation immediately after injection of the pain producing substance was counted, and again counted 15, 30, 45 and 60 minutes later. The total number of syndromes found is compared with that obtained in a control batch of mice.

Anti-inflammatory Effect (Carragenin oedema in rats).

The substance studied is administered orally 1 hour before intraplantar injection of Carragenin (0.05 ml of a 1 percent strength solution). The volume of the paw is measured by plethysmography 3 hours afterwards and compared with the initial volume. All the new compounds were tested at the same dose of mg/kg, a dose of which phenylbutazone produces 50 percent inhibition.

Antipyretic Efiect in guinea pigs Hyperthermy is produced by injecting a 50 percent solution of powdered milk subcutaneously at the rate of 2 ml per animal. The rectal temperature is measured during the three hours following the injection of milk. The compound under test is administered intraperitoneally in a dose of 125 mg/kg.

Depressant Effect on the righting reflex This is the loss of the righting reflex in mice after oral administration of the compound studied. Since the distinction between hypnotic effect and paralyzing effeet is not easy in mice, substances which showed an interesting activity in mice were also studied in rabbits. Anticonvulsant effect Pentetrazol at a dose of mg./kg. and strychnine at a dose of 2.2 mg./kg. are administered intraperitoneally to batches of 10 mice which had 30 minutes earlier received the substance being studied. The number of mice protected against tonic crisis and death is recorded.

General sedative effects Measurement of motility by activography The number of movements of a mouse placed in an individual cage is recorded by means of a crossed beam and photoelectric cell device. The number of movements during the first 5 minutes indicates the curiosity and that during the following 20 minutes the motility. The average number of movements for treated batches and for reference batches is compared.

Boosting of barbituric hypnosis (test of return to sleep) The substance studied is injected at a non-hypnotic dose after dissipation of the slumber induced by hexobarbital (75 mg./kg. administered intraperitoneally). The number of mice who lose the turning reflex and the average duration of slumber are recorded. Anti-depressant efiect (Antagonism of ptosis caused by reserpine in mice) The compound is administered intraperitoneally 1 hour before the reserpine (2 mg./kg. intraperitoneally) and the ptosis is measured every 30 minutes between the second and fourth hour after injection of the reserpine.

RESULTS Analgesic effect The compound of Example 33 (4-dimethylcarboxamidomethyl-6-butyl-3-oxo-2,3-dihydro-l ,4-benzoxazine) and the compound of Example 30 (2-ethyl-4-( acarboxamidoethyl )-6-methyl-3-dihydro- 1 ,4-benzoxazine) have a valuable effect. The table which follows gives the effective doses (ED 50) of these two compounds and shows that they are as active as aspirin but less toxic.

Compound LD 50 (oral Effective dose in mg./kg.) ED 50 (mg/kg.)

Aspirin 1000-1500 75 4-N-dimethylcarboxamidomethyl-8-chloro-3-oxo- 2,3-dihydro-l,4-benzoxazine (the product of Example 78) and 4-N-pentamethylenecarboxamidomethyl-S- chloro-3-oxo-2,3-dihydro- 1 ,4-benzoxazine (the product of Example 79) show interesting properties against visceral pain in Siegmunds test. When administrated orally, these compounds show a greater activity than aspirin in a dose of 100 mg./kg., and are less toxic.

Compound LD 50 inhibitions of lntraperitoneally orally painful symptoms Ex. 78 900 1500 61 Ex. 79 1000 7O Aspirin 495 10001500 54 Antipyretic effect The products of Example 41 (2-ethyl-4-carboxamidomethyl-6-chloro-3-oxo-2,3-dihydro-l ,4-benzoxazine), Example 42 (2-ethyl-4-(N-dimethyl-carboxamidomethyl)-6-chloro-3-oxo-2,3-dihydro-1,4-benzoxazine) and Example 20 (2-ethyl-4-carboxamidomethyl- 3-oxo-2,3-dihydro-1,4-benzoxazine) have valuable antipyretic properties, as shown in the following table.

Compound LD 50 (oral Maximum temperature in mg./kg.) lowering observed Ex. 41 1150 2C.

Ex. 42 1400 1.5C.

Ex. 20 1500 1.2C.

Aspirin 1000-1500 07C.

Compound intraper- PENETRAZOL STRYCHNINE itoneal dose in parparmgjkg. morttonic tial morttonic tial ality cricrisis ality crisis crisis -sis Control 100 100 0 20 Ex. 41 200 10 0 30 100 Ex. 42 10 0 100 100 100 0 Phenyl- 100 0 0 O 50 100 Sedative efiect RETURN TO SLEEP Compound intraper- Diminuitoneal tion of dose in spontaneous Slumber time, Duration of mgJkg. motility hexobarbital return to alone sleep Ex. 41 200 75 17 15" 74'15" Ex. 42 70 52 15 53 The products of Example 26 (2-ethyl-4- (morpholinocarboxylmethyl)-3-oxo-2,3-dihydro-1 ,4- benzoxazine), Example 34 (4-carboxamidomethyl-6- chloro-3-oxo-2,3-dihydro-1 ,4-benzoxazine Example 35 (4-(N-dimethylcarboxamidomethyl)-6-chloro-3- oxo-2,3-dihydro-l ,4-benzoxazine), and Example 39 (4- (piperidinocarboxylmethyl)-6-chloro-3-oxo-2,3- dihydro-l ,4-benzoxazine), have anti-inflammatory properties towards carragenin oedema, combined with more of less pronounced analgesic, antipyretic and central depressant properties.

The anti-inflammatory effects are set out in the following table.

Compound LD 50 (oral oral inhibition of in mgJkg.) dose oedema Ex. 26 1200 100 40.1 Ex. 34 1500 100 22.6 Ex. 35 1500 100 22.6 Ex. 39 1400 100 20.8

Anti-inflamm- Anti-pyretic activity atory activity ln- Intra- Oral hibition perit- Max. Temp. Compound LD 50 dose of oedema oneal lowering dose observed 87 200 23.9 200 1.1C. 86 1500 200 37.7 200 22C.

The product of Example 2 (4-(N-dimethylcarboxamidomethyl)-3-oxo-2,3dihydrol ,4-benzoxazine) has valuable anti-convulsant properties against the effects of pentetrazol. It is less effective against strychnine. It also exerts protective effects against electric shock in rats. For this reason it is therapeutically useful as an anti-epileptic. The test results are shown in the followmgtables. Anti-convulsant eflect towards Penetrazol and Strychnme LD 50 Pentetrazol Strychnine intraaperitoneal oral dose parparin in in tonic tial tonic tial mgJ mg./mg./ mortcriscrismortcriscriskg. kg. kg. ality is is ality is is Con trol 100 100 I lOO Compound of Ex.2 700 M00140 0 O 100 40 IQD 4-Carboxarnido-6-chloro-8-methyl-3-oxo-2,3- dihydro-l ,4-benzoxazine (the product of Example 72), 4-N-dimethylcarboxamidomethyl-o-chloro-8-methyl- 3-oxo-2,3-dihydro-1,4-benzoxazine (the product of Example 73), 2-ethyl-4-carboxamidomethyl-G-chloro-8- methyl-3-oxo-2 ,3-dihydro-l ,4-benzoxazine (the product of Example 69), and 2-ethyl-4-N-dimethylcarboxamidomethyl-o-chloro-8-methyl-3-oxo-2,3- dihydro-l,4-benzoxazine (the product of Example 70) show marked anti-pentetrazol properties, and the compounds of Example 69 and 70 antagonize the toxic effects of strychnine.

LD 50 Pentetrazol Strychnine Dose Comlntra- Ora! mg./ mortonic parmortonic parpound perikg. talcn'stial talcristial toneal ity es crisity es crises es ex.72 l000 l500200 0 O 100 90 100 ex.73 l000 l500200 0 0 100 90 100 ex.69 l500l00 20 10 90 50 90 10 ex.70 l000 l500200 20 10 90 60 100 Anti-convulsant effect against Electric Shock shock Dose Delay tonic flattened without rug/kg. crises crises crises Control lOO Compound 70 1 hour 0 60 40 of Ex. 2.

2 hours 40 6O The products of Example 18 (2-methyl-4-(N- dimethylcarboxamidomethyl )-3-oxo-2,3-dihydro-l ,4- benzoxazine), Example 19 (2-methyl-4-(piperidinocarboxylmethyl )-3-oxo2,3-dihydrol ,4-benzoxazine) Example 21 (2-ethyl-4-(N-dimethylcarboxamidomethyl)-3-oxo-2,3-dihydrol ,4benzoxazine and Example 22 (2-ethyl-4-(N-diethylcarbox amidomethyl)-3-oxo-2,3-dihydro-1 ,4-benzoxazine) have a depressant effect on the turning reflex in mice.

Ex. 22 M00 Compound Route of LD 50 Paralyzin g administrdose 50 ation (mg/kg) Ex. 56 oral 55G 35 Ex. 57 Oral 600 100 LP. 225 26 Ex. 59 [.P. I60 18 The anti-convulsant effect towards strychnine in mice of the product of Example 21 makes it a good muscular relaxing substance. The percentage protection against mortality and number of crises are shown in the following table.

Oral Dose STRYCHNINE PENTETRAZOL in mgjkg. mortality crises mortality crises The muscular-relaxing properties of the product of Example 21 were also established by the following tests:

a. Study on decerebtrated rats (see Streichenberger et at, Therapie, 20, 149, (1965)) This technique uses the inhibiting effect of the compound under test, when administered intravenously, on the ipsilateral flexing reflex caused electrically in decerebrated rats. Under these conditions the product of Example 21 produces a considerable reduction in the contraction of the anterior tibial muscle. This effect, which is already detectable at a dose of l mg./kg, increases in duration and intensity as the doses increase, as shown in the following table:

b. Study of the paralyzing effect on rabbits The compound is administered by slow perfusion. The minimum paralyzing dose (m P D) is established by the dropping of the head of the animal. The minimum fatal dose (m E D) is determined while the amount of product perfused is progressively increased. The m P D is about 10 mg/kg for a m F D of200 mg/kg. The ratio m F D/m P D= 20 is very advantageous.

The product of Example 21 furthermore has appreciable anti-inflammatory properties. When orally administered to rats at a dose of 50 mg/kg it causes a Toxicity Compound LD 50 intraperorally in lntraperitoneally mg/kg. itoneal diminin mg/kg. Dose ution In addition, 4-carboxamidomethyl-8-ch1oro-3-oxo- 2,3-dihydro-l,4-benzoxazine (the product of Example 77) antagonizes the depressant effect (ptosis) caused by reserpine in mice. This compound has an intraperitoneal LD 50 greater than 1,000 mg/kg. When administered intraperitoneally it causes in a dose of 25 mg/kg a 34 percent diminution of the ptosis, in a dose of 50 mg/kg a 71 percent reduction, and in a dose of 100 mg/kg 3 76 percent reduction of the ptosis.

The invention accordingly includes within its scope pharmaceutical compositions comprising one or more of the compounds of formula I in association with a compatible, pharmaceutically acceptable carrier or coating. Such compositions will ordinarily be in a form suitable for oral administration, e.g., tablets, pills, powders, syrups, or elixirs, or parenteral administration, e.g., sterile injectible solutions or suspensions. The carriers or coating and methods of formulation may be those customarily used in the art provided that they do not impare the valuable therapeutic properties of the active compound.

lclaim:

1. A 3-oxo-2,3-dihydro-1,4-benzo-xazine of the formula:

in which R represents hydrogen or straight or branched lower alkyl, R R and R are identical or different and each represents a hydrogen atom, straight or branched lower alkyl, a halogen atom, or lower alkoxy, R represents a hydrogen atom or lower alkyl, and R and R are identical or different, and each represents a hydrogen atom, phenyl or lower alkyl-substituted phenyl, lower alkyl, or lower hydroxyalkyl or R and R taken together with the nitrogen atom to which they are attached, form a heterocyclic five or six membered ring selected from the group consisting of pyrrolidyl, piperidyl, morpholinyl and piperazinyl.

2. A compound as claimed in claim 1 which is 4- dimethylcarboxyamidomethyl-6-tbutyl-3-oxo-2,3- dihydro-l,4-benzoxazine.

3. A compound as claimed in claim 1 which is 2- ethyl-4-carboxyamidomethyl-6-methyl-3-oxo-2,3- dihydro-l ,4-benzoxazine.

4. A compound as claimed in claim 1 which is 4-N- dimethylcarboxyamidomethyl-8-chloro-3-oxo-2,3- dihydro-l ,4-benzoxazine.

5. A compound as claimed in claim 1 which is 4-N- pentarnethylenecarboxyamidomethyl-8-chloro-3-oxo- 2,3-dihydro- 1 ,4-benzoxazine.

6. A compound as claimed in claim 1 which is 2- ethyl-4-carboxyamidomethyl-6-chloro-3-oxo-2,3-

dihydro-l ,4-benzoxazine.

7. A compound as claimed in claim 1 which is 2- ethyl-4-N-dimethylcarboxyamidomethyl-6-chloro-3- oxo-2,3 dihydro- 1 ,4-benz0xazine.

8. A compound as claimed in claim 1 which is 2- ethyl-4-carboxyamidomethyl-3-oxo-2,3- dihydrobenzoxazine.

9. A compound as claimed in claim 1 which is 2- butyl-4-N-pentamethylenecarboxyamidomethyl-6- methyl-3-oxo-2,3-dihydro-1 ,4-benzoxazine.

10. A compound as claimed in claim 1 which is 2- ethyl-4-N-diethyleneoxycarboxyamidomethyl-3-ox0- 2,3-dihydro-l ,4-benzoxazine.

11. A compound as claimed in claim 1 which is 4- carboxyamidomethyl-6-chloro-3-oxox-2,3-dihydrol ,4-benzoxazine.

12. A compound as claimed in claim 1 which is 4-N- dimethylcarboxyamidomethyl-6-chloro-3-oxo-2,3- dihydro-l ,4-benzoxazine.

13. A compound as claimed in claim 1 which is 4-N- pentarnethylenecarboxyamidomethyl-6-chloro-3-oxo- 2,3-dihydrol ,4-benzoxazine.

14. A compound as claimed in claim 1 which is 4-N- dimethylcarboxyamidomethyl-3-oxo-2,3-dihydro-l ,4- benzoxazine.

15. A compound as claimed in claim 1 which is 4- carboxyamidomethyl-6-chloro-8-methyl-3-oxo-2,3- dihydro-l ,4-benzoxazine.

16. A compound as claimed in claim 1 which is 4-N- dimethylcarboxyamidomethyl-6-chloro-8-methyl-3- oxo-2,3-dihydrol ,4-benzoxazine.

l7. A compound as claimed in claim 1 which is 2- ethyl-4-carboxyarnidomethyl--chloro-8-methyl-3- oxo-2,3-dihydro- 1 ,4-benzoxazine.

18. A compound as claimed in claim 1 which is 2- ethyl-4-N dimethylcarboxyamidomethyl-6-chloro-8- methyl-3oxo-2,3-dihydro-l ,4-benzoxazine.

19. A compound as claimed in claim 1 which is 2- methyl-4-N-dimethylcarboxyamidomethyl-3-oxo-2,3- dihydro- 1 ,4-ben2oxazine.

20. A compound as claimed in claim 1 which is 2- methyl-4-pentamethylenecarboxyamidomethyl-3-oxo- 2,3-dihydro-1 ,4-benzoxazine.

21. A compound as claimed in claim 1 which is 2- ethyl-4-N-dimethylcarboxyamidomethyl-3-oxo-2,3- dihydro-l ,4-benzoxazine.

22. A compound as claimed in claim 1 which is 2- ethyl-4-N-diethylcarboxyamidomethyl-3-oxo-2,3- dihyclro-l ,4-benzoxazine.

23. A compound as claimed in claim 1 which is 2- isopropyl-4-N-dimethylcarboxyamidomethyl-3-oxo- 2,3-dihydro,4-benzoxazine.

24. A compound as claimed in claim 1 which is 4- carboxyamidomethyl-S-chloro-3-oxo-2,3-dihydro- 1 ,4- benoxazine.

25. The compound of claim 1 which is 2-isopropyl-4- N-pentamethylenecarboxyamidomethyl-3-oxo-2,3- dihydrol ,4-benzoxazine.

26. The compound of claim 1 which is 2-butyl-4-N- dimethylcarboxyamidomethyl-3-oxo-2,3-dihydro 1 ,4- benzoxazine.

27. The compound of claim 1 which is 4-carboxyamidomethyl-3-oxo-2,3-dihydro-l ,4-benzoxazine.

28. The compound of claim 1 which is 2-methyl-4- carboxyamidomethyl-3-oxo-2,3-dihydro-l ,4-benzoxazine.

29. The compound of claim 1 which is 4-N-dimethylcarboxyamidomethyl-I-chloro-Ii-oxo-2,3-dihydro-l ,4-

benzoxazine.

30. The compound of claim 1 which is 2-ethyl-4-carboxyamidomethyl-7-chloro-3 -oxo-2,3-dihydro-l ,4- benzoxazine.

31. The compound of claim 1 which is 4-carboxyamidomethyl-8-chloro-3-oxo-2,S-dihydrol ,4-benoxazine.

32. The compound of claim 1 wherein R, is lower alkyl.

33. The compound of claim 1 in which all of R to R are a hydrogen atom.

34. The compound of claim 1 in which one of R and R is a halogen atom.

35. The compound of claim 1 in which one of R and R is a hydrogen atom.

36. The compound of claim 1 in which R; and R taken together with the nitrogen atom to which they are attached, form a heterocyclic five or six membered ring selected from the group consisting of pyrrolidyl, piperidyl, morpholinyl and piperazinyl.

37. The compound of claim 1 in which R is a hydrogen atom. 

2. A compound as claimed in claim 1 which is 4-dimethylcarboxyamidomethyl-6-t-butyl-3-oxo-2,3-dihydro-1,4-benzoxazine.
 3. A compound as claimed in claim 1 which is 2-ethyl-4-carboxyamidomethyl-6-methyl-3-oxo-2,3-dihydro-1,4-benzoxazine.
 4. A compound as claimed in claim 1 which is 4-N-dimethylcarboxyamidomethyl-8-chloro-3-oxo-2,3-dihydro-1,4-benzoxazine.
 5. A compound as claimed in claim 1 which is 4-N-pentamethylenecarboxyamidomethyl-8-chloro-3-oxo-2,3-dihydro-1,4 -benzoxazine.
 6. A compound as claimed in claim 1 which is 2-ethyl-4-carboxyamidomethyl-6-chloro-3-oxo-2,3-dihydro-1,4-benzoxazine.
 7. A compound as claimed in claim 1 which is 2-ethyl-4-N-dimethylcarboxyamidomethyl-6-chloro-3-oxo-2,3-dihydro-1,4 -benzoxazine.
 8. A compound as claimed in claim 1 which is 2-ethyl-4-carboxyamidomethyl-3-oxo-2,3-dihydrobenzoxazine.
 9. A compound as claimed in claim 1 which is 2-butyl-4-N-pentamethylenecarboxyamidomethyl-6-methyl-3-oxo-2,3-dihydro-1,4 -benzoxazine.
 10. A compound as claimed in claim 1 which is 2-ethyl-4-N-dieThyleneoxycarboxyamidomethyl-3-oxo-2,3-dihydro-1,4 -benzoxazine.
 11. A compound as claimed in claim 1 which is 4-carboxyamidomethyl-6-chloro-3-oxox-2,3-dihydro-1,4-benzoxazine.
 12. A compound as claimed in claim 1 which is 4-N-dimethylcarboxyamidomethyl-6-chloro-3-oxo-2,3-dihydro-1,4-benzoxazine.
 13. A compound as claimed in claim 1 which is 4-N-pentamethylenecarboxyamidomethyl-6-chloro-3-oxo-2,3-dihydro-1,4 -benzoxazine.
 14. A compound as claimed in claim 1 which is 4-N-dimethylcarboxyamidomethyl-3-oxo-2,3-dihydro-1,4-benzoxazine.
 15. A compound as claimed in claim 1 which is 4-carboxyamidomethyl-6-chloro-8-methyl-3-oxo-2,3-dihydro-1,4-benzoxazine.
 16. A compound as claimed in claim 1 which is 4-N-dimethylcarboxyamidomethyl-6-chloro-8-methyl-3-oxo-2,3-dihydro-1, 4-benzoxazine.
 17. A compound as claimed in claim 1 which is 2-ethyl-4-carboxyamidomethyl-6-chloro-8-methyl-3-oxo-2,3-dihydro-1,4 -benzoxazine.
 18. A compound as claimed in claim 1 which is 2-ethyl-4-N-dimethylcarboxyamidomethyl-6-chloro-8-methyl-3-oxo-2,3-dihydro -1, 4-benzoxazine.
 19. A compound as claimed in claim 1 which is 2-methyl-4-N-dimethylcarboxyamidomethyl-3-oxo-2,3-dihydro-1,4-benzoxazine.
 20. A compound as claimed in claim 1 which is 2-methyl-4-pentamethylenecarboxyamidomethyl-3-oxo-2,3-dihydro-1,4 -benzoxazine.
 21. A compound as claimed in claim 1 which is 2-ethyl-4-N-dimethylcarboxyamidomethyl-3-oxo-2,3-dihydro-1,4-benzoxazine.
 22. A compound as claimed in claim 1 which is 2-ethyl-4-N-diethylcarboxyamidomethyl-3-oxo-2,3-dihydro-1,4-benzoxazine.
 23. A compound as claimed in claim 1 which is 2-isopropyl-4-N-dimethylcarboxyamidomethyl-3-oxo-2,3-dihydro,4-benzoxazine.
 24. A compound as claimed in claim 1 which is 4-carboxyamidomethyl-8-chloro-3-oxo-2,3-dihydro-1,4-benoxazine.
 25. The compound of claim 1 which is 2-isopropyl-4-N-pentamethylenecarboxyamidomethyl-3-oxo-2,3-dihydro-1,4 -benzoxazine.
 26. The compound of claim 1 which is 2-butyl-4-N-dimethylcarboxyamidomethyl-3-oxo-2,3-dihydro-1,4-benzoxazine.
 27. The compound of claim 1 which is 4-carboxyamidomethyl-3-oxo-2,3-dihydro-1,4-benzoxazine.
 28. The compound of claim 1 which is 2-methyl-4-carboxyamidomethyl-3-oxo-2,3-dihydro-1,4-benzoxazine.
 29. The compound of claim 1 which is 4-N-dimethylcarboxyamidomethyl-7-chloro-3-oxo-2,3-dihydro-1,4-benzoxazine.
 30. The compound of claim 1 which is 2-ethyl-4-carboxyamidomethyl-7-chloro-3-oxo-2,3-dihydro-1,4-benzoxazine.
 31. The compound of claim 1 which is 4-carboxyamidomethyl-8-chloro-3-oxo-2,3-dihydro-1,4-benoxazine.
 32. The compound of claim 1 wherein R1 is lower alkyl.
 33. The compound of claim 1 in which all of R2 to R4 are a hydrogen atom.
 34. The compound of claim 1 in which one of R2 and R4 is a halogen atom.
 35. The compound of claim 1 in which one of R2 and R4 is a hydrogen atom.
 36. The compound of claim 1 in which R6 and R7 taken together with the nitrogen atom to which they are attached, form a heterocyclic five or six membered ring selected from the group consisting of pyrrolidyl, piperidyl, morpholinyl and piperazinyl.
 37. The compound of claim 1 in which R5 is a hydrogen atom. 